I. Field of the Invention
The present invention relates to carriers for filling cavities in aluminum extrusions with a thermal barrier material and, in particular, to a purging station associated with the nozzle injecting the barrier material.
II. Description of the Prior Art
Heretofore it has been known to feed lengths of aluminum extrusions of various sizes and shapes through an apparatus known as a filler carrier which is adapted to position the extrusion adjacent the nozzle of a plastic mixing and dispensing machine which will dispense measured amounts of uncured liquid plastic into a designated channel in the extrusion when the extrusion is beneath the nozzle. The plastic mixing and dispensing machines are generally of the type which have a two-component system for dispensing a urethane material in which the material is first mixed in a mixing chamber and then ejected under pressure through a nozzle into the designated channel of the extrusion as the extrusion is passed by the nozzle. Generally, such urethane thermal barrier materials solidify shortly after they have been mixed and injected into the channel of the extrusion. Generally the plastic will cure within ten seconds after the uncured liquid plastic has been ejected from the dispensing machine. Once the extrusion channel has been filled and the extrusion has passed by the nozzle, the dispensing machine must be kept operative so as to prevent the solidification or curing of the liquid plastic within the mixing chamber and dispensing nozzles thereof.
It is customary in such dispensing machines to first stop the flow of the plastic material upstream of the mixing chamber while the remaining material is ejected under pressure from the nozzle. Subsequent to ejection of the uncured liquid plastic, the mixing chamber and conduits from the mixing chamber to the nozzle are then flushed with a suitable chemical solvent. The solvent flush is then followed by a compressed air purge which insures that the mixing chamber, conduits and nozzle have been cleared of both the plastic material and solvent.
Because of the high monetary value of the mixing chamber of such dispensing machines, it is necessary to maintain the flow of the uncured plastic therethrough until the machine can be set up to insure that the flow of plastic can be terminated at a point upstream of the mixing chamber and that the flushing operation is operative and will properly function. This results in the dispersion of a considerable amount of the uncured plastic which is wasted and results in an unnecessary waste of money as the plastic is relatively expensive.
Unless some means are provided, the flushing operation of the solvent and pressurized air results in a considerable spraying of the work area. In particular, the surface area and related mechanical components of the filler carrier are exposed to the solvent and uncured plastic. This creates a very dirty environment which not only can cause damage to the machinery but delays their further subsequent use because a clean-up operation must be performed before new extrusions can be processed through the filler carrier.
It would therefore be desirable to provide a filler carrier and dispersing machine that can be operated in conjunction with each other and in which the dispersing machine can be switched from a plastic dispensing mode to a flushing mode in the shortest possible time without the heretofore problems of having waste materials sprayed upon machinery equipment, extrusions and personnel.